The premise of the marshmallow task is simple. Offer a kid a marshmallow. This marshmallow is theirs to eat, but if they can wait for you to leave the room and grab a second marshmallow, then they can eat both of the marshmallows when you return.

In the video up top, researchers at the University of Rochester revisit the marshmallow task, but they've thrown in an interesting twist: how long will children delay gratification after they've been primed to view the adult conducting the experiment as "reliable" or "unreliable"? Perhaps not surprisingly, the children assigned to the "reliable" condition tended to exhibit greater self-control than those in the "unreliable" condition, delaying gratification an average of four times longer. This, note the researchers in the latest issue of Cognition, suggests that a child's performance on the marshmallow task is moderated by rational decision-making. "Thus," write the researchers, "wait-times on sustained delay-of-gratiﬁcation tasks (e.g., the marshmallow task) may not only reﬂect differences in self-control abilities, but also beliefs about the stability of the world."